ELDRIDGE, IA (WQAD/CNN) — A terminally-ill cancer patient and his family, whose explanation for growing and using marijuana were not allowed as evidence, were found guilty of drug charges in Scott County Court.

Benton and Loretta Mackenzie and their son, Cody, faced charges after 71 marijuana plants were seized by police in May 2013. Mackenzie admitted in testimony Tuesday, July 3, 2014, that the plants were his.

Mackenzie claimed he grew the plants to harvest cannabis oil to treat pain he suffers from angiosarcoma. Judge Henry Latham ruled Mackenzie’s reasons for growing the plants were not admissible as evidence in the trial.

“The sheriff’s department, the prosecutor the judges they all they all act like I’m malingering, like I’m faking,” Mackenzie said. “I’m dying. I should have been dead years ago.”

A Scott County jury convicted Benton and Loretta Mackenzie each of manufacturing marijuana, conspiracy, violation of the drug tax stamp act and possession of drug paraphernalia, according to Scott County Attorney Mike Walton.

Cody Mackenzie was convicted of misdemeanor possession of marijuana and paraphernalia, Walton said.

“After the verdict, Mackenzie stipulated that he has been twice before convicted of drug felonies. In 2011 both Benton and Loretta Mackenzie were convicted of Possession with Intent to Deliver. They were on probation for those charges when charged with the current charges. In 2000 Benton Mackenzie was convicted of Possession with Intent to Deliver,” Walton said.

Mackenzie faces mandatory prison time for the conviction. Sentencing was reportedly set for August 28, 2014.